ISSUE-99: use "findDocumentLinks2" method

[mrmlnc]

This is a fix for #99.

Yeap, right now it looks dirty. But in the future I would like to separate the concept of parser and link search. Something like:

https://github.com/microsoft/vscode/blob/2bb6cfc16a88281b75cfdaced340308ff89a849e/extensions/css-language-features/server/src/cssServerMain.ts#L231-L249

[octref]

That's ok for now 👍
Parser should return whatever that's in the import path, and it should be up to a link resolver to resolve the dependencies according to SASS logic.